Mechanical axial vibration in membrane separation treatment of effluents

ABSTRACT

Apparatus and methods are disclosed for mechanical axial vibration in membrane separation treatment processes. The apparatus includes a separation membrane element having an axial dimension, a membrane support structure having the element therein, and means for vibrating the membrane element (hydrodynamically or using motors) in the axial dimension.

RELATED APPLICATION

This application is a Division of now pending U.S. patent applicationSer. No. 12/452,778 filed Jan. 22, 2010 by the inventors herein andentitled Mechanical Axial Vibration In Membrane Separation Treatment ofEffluents, which prior application is a continuation of U.S. patentapplication Ser. No. 11/888,512 filed Aug. 1, 2007 by inventorsincluding the inventors herein.

FIELD OF THE INVENTION

This invention relates to effluent treatment, and, more particularly,relates to membrane separation treatment of effluents.

BACKGROUND OF THE INVENTION

Most industrial and municipal processes require water treatmentfacilities to treat effluents returned to the environment. Suchfacilities typically represent a significant investment by thebusiness/community, and the performance of the facility (or failurethereof) can seriously impact ongoing operations financially and interms of operational continuity.

Moreover, not all effluent treatment requires the same technologies.Industrial effluents (such as is found at coal bed methane facilities oroil production sites, for example) all have different particulate,pollutant and/or biomass content inherent to both the industrialprocesses as well as the particular water and soil conditions found atthe site. Municipal requirements would likewise vary depending ondesired end-of-pipe quality and use (and again depending on the feedwater present at the site).

Filtering by membrane separation techniques is known. Membrane elementsin such use require constant maintenance and frequent cleaning orreplacement. Vibratory means have been heretofore known and/or utilizedin membrane separation to reduce maintenance requirements. These haveemployed horizontal vibratory torsional motion, and often require use ofproprietary one source only custom membrane modules. Furtherimprovements could thus still be utilized.

SUMMARY OF THE INVENTION

This invention provides methods for mechanical (motorized,electromagnetic or hydrodynamic) axial vibration in membrane separationtreatment of effluents. The methods allow use of readily available, andthus less costly, conventional membrane elements and/or modules. Axial,linear operation allows mounting of membrane modules in a vertical flowgravity assisted position, with adjustable crossflow operationaccommodated.

The methods are adapted to apparatus including a separation membraneelement having an axial dimension, a membrane support structure havingthe element therein, and means for vibrating the membrane element in theaxial dimension. Crossflow pumping is connected with the supportstructure. In one embodiment, the support structure includes a membranehousing, the vibrating means including a fluid pump and springarrangement for oscillating the membrane element. In another embodiment,the support structure includes a tube for receiving and securing themembrane element, the tube and element together defining a membranecartridge, the cartridge axially mounted in a containment housing andmovable axially therein by the vibrating means (hydrodynamically orelectromagnetically, for example). In yet another embodiment, thevibrating means are motors for vibrating a plurality of elements on acommon platform.

The methods of this invention include the steps of locating a membraneelement in a support structure and feeding effluent for treatment intothe support structure. Axial vibration of the membrane element in thesupport structure is initiated without securement of the membraneelement to a source of vibration, and treated effluent is withdrawn fromthe support structure. The membrane element is located in the supportstructure without attachment to the support structure or other structureoutside the support structure. Vibration of the membrane element in thesupport structure in the axial dimension is accomplished using any ofhydrodynamic, electromagnetic and mechanical methods.

In one embodiment, the membrane module is positioned in a containmenthousing configured for free axial movement of the membrane moduletherein, extent of axial movement being adjustably limitable. Axialvibration is hydrodynamically activated in the containment housing aslimited.

Vibration direction is axial and preferably perpendicular to the floorof the installation for gravity assisted membrane separation systems.The shear wave produced by axial vertical membrane vibration causessolids and foulants to be lifted off membrane surfaces and remixed withretentate flowing through the parallel or tunnel spacer or otherspecially designed spacers of spirally wound elements or through flowchannels of tubular or capillar membrane elements. Movement continuityis maintained through adjustable crossflow, reducing further additionalmembrane fouling tendency. The vibration curve is preferably a regularcurve, which corresponds mathematically to a zero centered sine orcosine, a sinusoidal or simple harmonic. The amplitude is preferablysteady and frequency high.

It is therefore an object of this invention to provide methods formechanical axial vibration in membrane separation treatment ofeffluents.

It is another object of this invention to provide methods for mechanicalaxial vibration in membrane separation treatment of effluents thataccommodates use of readily available, conventional membrane elementsand/or modules.

It is another object of this invention to provide a method for axialvibration in membrane separation treatment of effluents that includesthe steps of locating a membrane element in a support structure, feedingeffluent for treatment into the support structure, initiating axialvibration of the membrane element in the support structure withoutsecurement of the membrane element to a source of vibration, andwithdrawing treated effluent from the support structure.

It is still another object of this invention to provide a method foraxial vibration in membrane separation treatment of effluents includingthe steps of locating a membrane element having an axial dimension in amembrane support structure without any direct attachment of the membraneelement to the support structure or other structure outside the supportstructure, and vibrating the membrane element in the support structurein the axial dimension one of hydrodynamically, electromagnetically andmechanically.

It is yet another object of this invention to provide a method for axialvibration in membrane separation treatment of effluents which includesthe steps of positioning a membrane module in a containment housingconfigured for free axial movement of the membrane module therein,adjustably limiting extent of axial movement of the membrane module inthe containment housing, and hydrodynamically activating axial vibrationof the membrane module in the containment housing as limited.

With these and other objects in view, which will become apparent to oneskilled in the art as the description proceeds, this invention residesin the novel construction, combination, and arrangement of parts andmethods substantially as hereinafter described, and more particularlydefined by the appended claims, it being understood that changes in theprecise embodiment of the herein disclosed invention are meant to beincluded as come within the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a complete embodiment of theinvention according to the best mode so far devised for the practicalapplication of the principles thereof, and in which:

FIG. 1 is a block diagram illustrating phased functions in an effluenttreatment regime;

FIG. 2 is a diagram illustrating a first membrane technology of thisinvention utilizable in steps directed to the primary (effluentpolishing) treatment of effluents;

FIG. 3 is a diagram illustrating a second membrane technology of thisinvention utilizable in steps directed to the primary treatment ofeffluents;

FIGS. 4 a and 4 b are illustrations of coil structures utilizable in thetechnology of FIGS. 2 and 3;

FIG. 5 is a detailed view illustrating coil cooling utilizable in thetechnology of FIGS. 2 through 4;

FIG. 6 is a diagram illustrating apparatus for internal concentrationpolarization control in the technology of FIGS. 2 through 4;

FIG. 7 is a diagram illustrating one membrane deployment optionutilizable in primary treatment steps of this invention;

FIG. 8 is a sectional illustration of a crossflow pump of this inventionutilized in various membrane separation technologies;

FIG. 9 is a sectional illustration of an improved degasser column usedwith the membrane systems of this invention;

FIG. 10 is a flow distributor and discharge equalizer deployed, forexample, with the membrane systems of this invention;

FIGS. 11 a and 11 b are diagrams illustrating a high frequencyoscillating membrane system utilizable in primary treatment of thisinvention;

FIG. 12 is a sectional diagram illustrating a second embodiment of thehigh frequency oscillating membrane system;

FIG. 13 is a partial sectional illustration of the oscillating membranesystem of FIG. 12;

FIG. 14 is a detailed sectional illustration of the upper part of theoscillating membrane system of FIG. 13;

FIG. 15 is a detailed sectional illustration of the lower part of theoscillating membrane system of FIG. 13;

FIG. 16 is an illustration showing function of the spirally woundmembrane elements of the oscillating membrane system of FIG. 13 (alsoemployable in other oscillating systems shown herein);

FIG. 17 is a diagram illustrating an alternative deployment of theoscillating membrane system of FIG. 13;

FIG. 18 is a sectional illustration of a vibratory seal arrangement forthe oscillating membrane system of FIGS. 13 and 14;

FIG. 19 is a sectional illustration of a high shear embodiment of theoscillating membrane system of FIGS. 12 through 17; and

FIG. 20 is a sectional illustration of a draw-off utilizable in the highshear embodiment of FIG. 19.

DESCRIPTION OF THE INVENTION

As background, FIG. 1 shows steps of an effluent treatment regime. Theoption numbers located at three-way valves 401 refer to automated oroverride manual flow control options for different treatment regimes.Stage 403 (step 1) is a dual strainer receiving feed effluent andremoving particulates down to about 500 μm (for example, the model 120dual strainer produced by Plenty Products, Inc.). Stage 405 (step 2)provides oil separation from the feed flow utilizing a separator (forexample, a Highland Tank & Mfg. Co. R-HTC Oil/Water Separator withPetro-Screen and parallel corrugated plate coalescers). Stage 407 (step3) is an automatic backflush filter providing particle removal down tothe 100 μm range or better (a TEKLEEN self cleaning bell filter setupwith GB6 electric controller by Automatic Filters, Inc., or similarfilter setups by Amiad Filtration Systems, could be utilized forexample).

Stage 409 (step 4) provides inline direct feed effluent (water) heating.Feed water heating is required in many treatment settings due toseasonal operations, and further benefits many downpipe treatmentoptions by breaking feed water alkalinity, enhancing CH₄ gas removal,ensuring proper membrane (where present) permeate flux for an overallconstant permeate flow yield, and the like. Either of two types ofinline heating systems may be utilized, as more fully detailed below.

Stage 411 (step 5) is a first suite of pre-treatment apparatus includingeight apparatus (all eight are preferred, but fewer could be provided insome applications). These apparatus provide, as more fully detailedbelow, on-line diffusive effect (ODE) membrane aeration, fluid densityreduction, modified vacuum tower or cascade series waterfall degassing,air stone degassing, modified venturi gas evacuation, fine filtration,lamella plate clarification, and sludge chamber concentration.

Stage 413 (step 6) is a second suite of pre-treatment apparatusincluding ten apparatus (all ten are preferred, but fewer could beprovided in some applications). This stage provides pH adjustment (viaan injection pump 302), chemical dosing (via an injection pump 304,ODE/IDI (inline diffusive ionization) membrane aeration, ionized air/gastreatment, electrocoagulation, dissolved air/gas flotation, vacuumintroduced cyclone separation, vacuum degassing, lamella plateclarification, and sludge chamber concentration.

Stage 415 (step 7) provides a bag filter and/or belt filter assembly(for example, fabric filtration systems sold by SERFILCO) for filtrationdown to about the 1 μm range. Stage 417 (step 8) is a homogenizing andbuffer tank with pH adjustment and chemical dosing (at injection pumps306 and 308, respectively). Stage 419 (step 9) is the first of theprimary, effluent polishing treatment array (stages 419 through 433,steps 9 through 16), and may include any of several membrane treatmentapparatus in accord with this invention as more fully detailedhereinafter providing nanofiltration, and/or known ion-exchangetreatment technology. Stage 419, as is apparent, is an option forup-concentrating effluent to increase overall flow yield.

Stage 421 (step 10) provides antifouling and antiscaling chemicaltreatment to prevent fouling and scaling of membranes by keeping lowmolecular weight components in solution (foremost of which are divalentand multivalent cations). Known variable speed tubing pumps could beutilized for insertion. Stage 423 (step 11) provides filtration forremoval of low molecular weight components (Al, Fe, Mg and Mn, forexample) and/or colloidals utilizing membrane treatment nanofiltrationand/or ion-exchange treatment. Stage 425 (step 12) provides a buffertank for step 14 for process flow control (for example a Snyderhorizontal leg tank by Harrington). Stage 427 (step 13) providesantiscaling chemical treatment addressing monovalent and a few divalentcations and anions (Ba, Ca, Na, Sr, CO₃F, HCO₃, and SO₄ for example).Again, known variable speed tubing pumps could be utilized forinsertion.

Stage 429 (step 14) addresses removal of low molecular weight components(salts, for example) utilizing reverse osmosis membrane treatment and/orion-exchange treatment. Stage 431 (step 15) is a high pressure buffertank providing flow control for step 9 and/or 16. Stage 433 (step 16)provides up-concentration of concentrate flow from stage 429 to furtherincrease flow yield, and may utilize reverse osmosis membrane treatment,ion-exchange treatment and/or high efficiency electrodialysis technology(for example, a HEED assembly by EET Corporation), a hybrid processincluding both electrodialysis and reverse osmosis approaches.

Stage 435 (step 17) is a suite of four post-treatment apparatus as morefully detailed herein below, and including activated carbon filtrationfor gas absorption (Ametic filter chambers by Harrington, for example),sodium absorption ratio compensation, utilizing a dolomite filter forexample, UV treatment (for example, an SP or SL series unit fromAquafine Corporation), and membrane aeration for O₂ saturation(preferably utilizing an ODE system in accord with yet another aspect ofthis invention).

Stage 437 (step 18) provides bio-monitoring utilizing a 10 gallonaquarium with the operating volume passing through either a sterilizeror other aquarium device to prevent in situ bio-contamination from wasteand nutrients. The sterilizer or other device must match the maximumproduced permeate flow of at the rate of approximately one gallon perminute for real time bio-monitoring. Since the sterilized water istypically being mixed with unsterilized water, it is not possible tocompletely purify it, but a sterilized percentage exceeding 99.9% isacceptable for the bio-monitoring step sensitivity. Stage 439 (step 19)conventionally provides waste collection and purified feed return.

Regarding the ion-exchange treatment alternative at stages 419, 423,429, and 433 (steps 9, 11, 14 and 16), this process is a well knownwater treatment process for removing ions from solution by exchangingcations or anions between the dissolved phase and counter ions on amatrix such as organic zeolite, in which Ca₂ ⁺ ions in solution displaceNa ions in the zeolite, montmorillonite (a colloidal bentonite clay) orsynthetically produced organic resins, for example.

An organic ion exchange resin is composed of high molecular-weightpolyelectrolytes that can exchange their mobile ions for ions of similarcharge from the surrounding medium. Each resin has a distinct number ofmobile sites that set the maximum quantity of exchanges per unit ofresin. Ion exchange reactions are stoichiometric and reversible.

Commercially available ion-exchange treatment technology can be utilizedalone as an alternative to the hereinafter detailed membrane treatmenttechnology or may supplement specific membrane technology. Theimplementation of ion-exchange technology depends on the specificapplication and project economics (the less complex and labor-intensivestate of the art ion exchange technology may be used as a singlepolishing step instead of membrane treatment where cost is a factor anddesired treatment outcomes warrant the tradeoff).

In some settings, primarily depending on the intended use of thepurified water, complete deionization (replacement of all cations by thehydrogen ion as well as replacement of all anions by the hydroxide ion)may be required. In such case, commercial cation- and anion-exchangetechnology will be employed as a polishing treatment step alone or inaddition to membrane treatment (again depending on the end-of-pipeoutcomes desired). For example, feed water with total dissolved solidsof less than about 500 mg/L is ideally suited for ion exchangetechnology in combination with reverse osmosis membrane treatment. Inother words, after membrane treatment at step 14 (429), the producedpermeate is fed into a strongly acidic cation exchanger followed by astrongly basic anion exchanger (substituting for both steps 15 and 16).Such systems are commercially available from KINETICO, REMCO ENGINEERINGand others.

Membrane treatment and other treatment systems (205 in some of theFIGURES), including stages 419 through 433 (steps 8 through 16), may berealized by deployment of various types of apparatus and systems,particularly at steps 9, 11, 14 and 16 (steps 8, 10, 12, 13 and 15 areprimarily directed to homogenization and process buffering and/orchemical metering, and have been addressed hereinabove). Ion-exchangetreatment and HEED systems utilizable herein have already beenaddressed. In addition V-SEP series L/P systems, while not preferred,could be utilized at stages 419, 423, 429 and 433 for analytics as wellas nanofiltration and reverse osmosis filter installations.

At stage 419, high frequency nanofiltration systems as discussedhereinbelow could be employed. However, in accordance with one aspect ofthis invention, FIGS. 2 through 5 illustrate an axial (linear) vibratorymembrane separation apparatus and methods for forward osmosis. Thisaspect of the invention relates to low amplitude, axial vibratorymembrane separation apparatus (both nanofiltration and reverse osmosisfiltration) called quaking recycle membrane separation technologyemployed with forward osmosis technology. Forward osmosis technology isemployed to supplement the quaking membrane nanofiltration and/orreverse osmosis technology, the hybrid application incorporated into anintegrated apparatus (high frequency forward nanofiltration or highfrequency forward reverse osmosis apparatus).

Heretofore known forward osmosis technology uses the osmotic pressuredifferential across a membrane, rather than the hydraulic pressuredifferential, for filtration. The osmotic pressure differential isprovided by a recyclable solute composed of a mixture of salts, thethermally recyclable salt solution called “draw solution”. Drawsolutions typically used include ammonium bicarbonate (NH₄HCO₃),ammonium carbonate (NH₄)₂CO₃, ammonium carbamate NH₄NH₂CO₂;(H₄NO)(CONH₂; H₂N—CO—O—NH₄), and can preferably include magnetoferritinin solution. The concentration of solutes in the thermally recyclabledraw is required to have a higher osmotic pressure than the osmoticpressure of the concentration of solutes in the feed water (oftenbrackish). Common spiral-wound membranes have not been heretoforeutilized for forward osmosis because a liquid stream cannot be forced toflow on the support side (permeate side) inside the envelope, where theporous polymer layer further increases the internal concentrationpolarization. The apparatus of this aspect of the invention employstubular or hollow fiber membrane modules, rather than spiral-woundmembrane elements.

The hybrid quaking membrane plus forward osmosis process and apparatusof this invention secure permeate continuity of the present art forwardosmosis technology (generating extreme turbulence on both sides of theforward osmosis membrane (feed side and draw side) to support permeatecontinuity), provide nondestructive, vibratory membrane separation forcommercially available forward osmosis membranes, and reduce thepotential tendencies of concentration polarization, scaling and foulingof forward osmosis membranes.

Turning to FIGS. 2 to 5, the hybrid quaking membrane plus forwardosmosis process and apparatus is illustrated with the quaking membraneassembly at 2401 and recycle and reconcentrating closed loop system at2501. In the combined apparatus, self-supported, semi-permeable orhollow fiber tubular membrane 2403 is used as a forward osmosis membraneoperating in a quaking membrane process. Such tubular and hollow fibermembranes have no thick support layer as in spiral-wound, flat sheet,asymmetric membranes, thus minimizing internal concentrationpolarization. Membranes of this type are commercially available.

The quaking membrane process is low amplitude and high quakingfrequency, generating low shear energy and therefore a gentle treatmentin the epoxy potting compound of tubular or hollow fiber membrane 2403.The quaking energy significantly lowers already low externalconcentration polarization, and has a positive effect on internalconcentration polarization as well. Sufficient turbulence is generatedon both sides of tubular or hollow fiber membrane 2403 (external andinternal) for securing continuation of increased flux performancerequired by the forward osmosis process. The process thus yields ahigher permeate production with less concentrate for disposal andrequires less up front pre-treatment for the feed, while using lessenergy compared to conventional reverse osmosis/nanofiltrationtechnology because little or no hydraulic pressure is needed as adriving force for separation.

For a continuously operated forward osmosis process, it is necessarythat the membrane module design allows liquids to flow freely on bothsides of membrane elements. Cellulose triacetate is the preferredmaterial used in membrane 2403 (TOYOBO Hollosep hollow fiber membranes,for example). Low pressurized, recirculating feed water flows inside ofthe hollow fiber tubes of the membrane module 2403 from low pressurefeed recirculation pump 2405. The gravity-assisted feed flow is inducedat the top of the axial vibrating, hollow fiber module 2403.

Quaking membrane module 2403 can either be operated in a vertical orinclined position, quaking membrane movement is provided by means ofquake generator such as high pressure diaphragm pump 2407. The lowpressurized, draw solution flows counter currently to the feed on theoutside of the hollow fiber tubes. The draw enters at the bottom ofmembrane module 2403 and exits at the top. Forced draw circulation flowis provided by vacuum and compressor pump 2503 (FIG. 3). Theconcentration of the draw solution is diluted as the high osmoticpressure of the solution draws water through the semi-permeable membranefrom the feed medium of lesser osmotic pressure. This, in turn, requiresa reconcentration of the draw solution for the continuous desalinationprocess.

The diluted draw solution is thermally recycled and reconcentrated in aclosed loop system, which yields potable water. The closed loop systemconsists of two heat exchangers 2505 and 2507, a stripper column 2509,and buffer tank 2511. In the closed loop, the draw solution diluted withwater is first lightly heated to 30° to 50° C. in heat exchanger 2505.The heated draw exits heat exchanger 2505 from the top and is siphonedinto stripper column 2509. Stripper column 2509 packing includes eitherraschig rings or berl saddles. Stripping takes place the column, thepacking providing the necessary increased area and turbulence to achievea desired draw solution conversion from a liquid to a vapor phase withthe nonvolatile water precipitating out of the draw solution.

The lightly heated, liquefied and diluted influent (consisting of waterand its soluble light volatile draw components) is distributed (at sprayhead 2512, for example) at the top of packed column bed 2513, flowingdown through the bed where the large transfer area and the vacuumassistance of pump 2503 allows the volatile components of the diluteddraw to convert into an effluent vapor phase in the upper column portionand yielding potable water dilution water from the lower column portion(the treatment product of this apparatus). Vacuum and compressor pump2503 is configured to handle a large vapor volume on its suction sideand compressing the vapor on its pressure side, and transfers thepressurized vapor from stripper column 2509 into the top of second heatexchanger 2507 for compression heat removal from the compressed vapormixture. Cooling is provided by means of fresh cold feed water.

The cooling the vapor phase yields a condensate of a highly concentratedsolute mixture and thus generates a recycled draw solution of initialconcentration strength. The vapor mixture condensate is discharged fromexchanger 2507 into buffer tank 2511. Tank 2511 includes automaticaeration and de-aeration device 2517 to avoid the passage of residualvapor into hollow fiber module 2403. Treated water is transferred out ofcolumn 2509 by centrifugal-vacuum pump 2519 while retentate particleseparation is achieved via hydrocyclone separator 2409 (FIG. 2). Theupper module suction provides motive force to the recycled draw solutionfor flowing continuously from the lower permeate suction connection ofmodule 2403 upwards and towards the upper permeate discharge connection,while the feed flows counter current to the draw downwards inside ofhollow fiber module 2403.

The apparatus of FIGS. 2 and 3 is adapted for use not only withcommercially available semi-permeable tubular and/or hollow fibermembranes modules, but also for forward osmosis specialized spiral-woundmembranes when and if they become commercially available. The apparatusand processes can be used in applications for any brackish watertreatment, higher contaminated CBM water treatment, overflow treatmentof biological, defecated, municipal waste water for irrigation, cleaningprocesses for airplane and other public transportation wash waterrecycling, processing of bilge water, processing of wash water forcombat vehicles after active and practice missions, and waste waterprocessing for the pharmaceutical and chemical industry.

The quaking membrane coupled with the forward osmosis process allows asubstantial concentration upgrading at stage 419 at a significantlyreduced energy requirement compared to conventional membrane separationprocesses, and could be employed as well at stages 423, 429 and/or 433.Depending on the application, quaking membrane technology provides highrecovery relative to conventional nanofiltration and/or reverse osmosistechnology. Reduced scaling and fouling tendencies of the apparatus andprocesses reduce costs associated with pre-treatment stages used inconventional nanofiltration and reverse osmosis technology.

Quaking frequency is variable in the range of 1 to 100 Hz depending onconfiguration. Quake amplitude has a relatively wide adjustable range of0.2 to 2.0 mm. Quaking membrane movement can be generated either by anyof electrical, hydraulic or mechanical means through an adjustable highfrequency generator. Electrical means can include electromagnetic linearreciprocating membrane motion apparatus through a frequency-controlled,modified linear motion motor assembly wherein frequency and amplitudecan be adjusted dynamically over a greater range (from 1 to 100 Hz.—seeFIGS. 4 and 5).

Modified motor assembly 2601 is shown in FIGS. 4 a and 4 b having anupper stator coil section 2603 and lower stator coil section 2605, upperand lower (upper components only being shown in FIG. 4 b) fluidtransferring end pieces 2607 being equipped with encapsulated,high-energy neodymium, iron-boron, reciprocating permanent magnetsleeves 2609. The nonmagnetic outer housing 2610 has upper (and lower,not shown) stator 2611 thereat between retainers 2613. The statorscontain the electromagnetic coils, which utilizes 3-phase direct drive,brushless technology. The stator's length and diameter set the forcelevel, while the sleeve length determines the amplitude height.

Motor 2601 uses a dual synchronous design wherein two stators and twopermanent magnet sleeves are spaced over the entire length of themembrane. These dual linear motors are operated synchronously thusproviding positive linear reciprocating motion over the entire length ofthe membrane. Quaking membrane cartridge at 2403 floats and is supportedbetween an upper recoil spring system and the lower support structurespring system (both at 2403), thus isolating membrane cartridge movementtherebetween. Spring rate is adjustable for equalization of the statorcoil force requirement between upper and lower stator coils 2611, withforce requirements based on the chosen operational quaking frequency andamplitude.

As can be appreciated, the membrane cartridge rides up and down betweentwo resilient spring isolation systems within a stationary (housing alsoat 2403), whereas the motive reciprocating forces are provided by meansof dual synchronously operating linear motor assembly 2601. The twospring systems are configured to be adjustable for vibrationtransmissibility and damping efficiency (the spring system's ability todissipate oscillatory energy and thus not transfer the energy to theentire quaking membrane module 2403).

The modified linear motor assembly 2601 is essentially an electric motorthat has its stator configured and positioned so that, instead ofproducing rotation, it produces a linear force along its length. Asshown in FIG. 5 stator coil cooling can be accomplished utilizing a coldfeed water stream (for example, from the same cold feed stream feedingheat exchanger 2507) fed by appropriate piping to port 2701 ofring-shaped cooler 2703 mounted between retainer disks 2705 adjacent tostator coil 2411. Feed at port 2701 is constantly replenished andrecycled out at port 2707 connected at heat exchanger 2505.

Feedback in the forward osmosis system can be bypassed, if operations inquaking membrane mode only is preferred, by simple valving preventingre-osmosis of clean permeate. Three-way ball valve 2521 functions as aselector valve for quaking membrane plus forward osmosis mode operationsor quaking membrane mode operations only.

Osmotic pressure differential in the foregoing quaking membrane forwardosmosis apparatus and methods is preferable provided by a magneticallyrecyclable solute composed of magnetic mixture of soluble salts. The useof magnetoferritin is known but requires removal from the aqueous streamby means of electromagnetic separation. To minimize problems associatedtherewith and with the problem of concentration polarization, FIG. 6shows an ultrasonically active draw solution dispersion system in accordwith yet another aspect of this invention.

Alternating electrical energy from ultrasonic generator 2801 isconverted to an alternating magnetic field at coil 2803 in protectivehousing 2805 held around the outer housing of membrane module 2403 byretaining disks 2807. Coil 2803 extends substantially the entire lengthof module 2403. Generator 2801 is adjustable. The oscillating magneticfield induces hydrodynamic dispersion forces (turbulence) at ultrasonicfrequencies in the ultrasonically active draw solution includingmagnetoferritin. The turbulence is at the internal boundary layer of themembrane thus minimizing internal concentration polarization. Externalconcentration polarization is controlled by using a low pressuremagnetically coupled centrifugal feed pump with an elevated output ratefor producing external feed flow turbulence.

FIG. 7 shows one arrangement of components in a polishing treatmentarray 205 using membrane treatment systems especially concentrating onthe integration of the membrane treatment systems of stages 423 (step 11using the nanofiltration membrane treatment option) and 429 (step 14using the reverse osmosis membrane treatment option). These two stages(implementing membrane processes) separate dissolved solids from thepre-treated water. The selection of specific membranes and spacermaterial are based on test results (for example, from on-sitethree-dimensional test cells such as those shown in U.S. Pat. No.6,059,970). The systems are set to operate at moderately to highpressures and typically employ high speed gravity assisted geometrieswith selected variable crossflow capabilities.

Nanofiltration membrane implementation of stage 423 is a multistageconfiguration, operating in series. The array includes, for example,three pressure vessels 2901 each having a single membrane. The primaryfunction of nanofiltration membrane treatment is the removal of thefinest colloidal matter. The separated colloidal matter is removed withthe nanofiltration concentrate. The produced nanofiltration permeateserves as feed the next membrane and, ultimately, for reverse osmosisimplementation of stage 429.

The reverse osmosis implemented array of stage 429 includes, forexample, two stages, with two membranes 2903 operating in parallel inthe first stage feeding a third membrane 2905 in the second stage. Asshown, each stage thus implemented has its own pressure pump andcrossflow pump 2907, 2909 and 2911 and 2913, respectively.Nanofiltration stage 423 has a maximum operating pressure of 35 bar (508psi), and a crossflow pump maximum rating of 50 gpm at a maximum of 60psi in a 750 psi environment. Reverse osmosis stage 429 has a maximumoperating pressure of 70 bar (1015 psi), and a crossflow pump rating ofmaximum rating of 10 gpm at a maximum of 45 psi in a 1,200 psienvironment. System operating pressure is regulated through bypassregulators 2914 and 2920.

At this time, the most economical ready-made nanofiltration membraneshape is a flat membrane sheet in a spiral wound membrane element. Aspiral wound element consists of multiple membrane pockets (for example4-16 pockets), the spiral wound pockets terminating into a centralizedcollecting pipe. Special parallel polypropylene spacers of 80 milthickness are preferred and complete the membrane (spiral woundnanofiltration membrane elements from Nadir with a practical neutralsurface voltage (zeta potential), for example).

The nanofiltration special spacing materials (spacers) are especiallyeffective in applications with high suspended solids (colloidal)concentration. Since the primary purpose of the nanofiltration is toremove all suspended solids rather than dissolved solids (such assalts), these types of spacers with their larger spacing between themembrane surfaces are preferred. A smaller membrane spacer for otherapplications could be use (for example, having 33 mil diamond spacer).

Alternatively, to maintain maximum processing flexibility at stage 423,low and ultra-low pressure reverse osmosis membranes could be used(where total dissolved salts are an issue). If nanofiltration membranesare employed, crossflow pump 2909 output flow must be turned down atbypass valve 2915 for a lesser brine to permeate ratio to achieve a moredesirable permeate quality.

Reverse osmosis and/or HEED assembly buffer tank and at stages 425 and431 can be any suitable tank and containment basin (for example, a threeleg tank by SNYDER). Stage 427 (step 13) is interposed to reducescalants in reverse osmosis processes. Bicarbonate (HCO₃) is present inmany post production waters presented for treatment (such as CBM water,for example). Many produced CBM waters are near saturation in dissolvedbicarbonate. When these waters are concentrated in a reverse osmosissystem, calcium carbonate will be one of the first salts to precipitate.Calcium Carbonate scaling potential can be estimated using stabilityindex calculations.

Prevention of calcium carbonate precipitation in nanofiltration orreverse osmosis systems is aided by injection of sulfuric acid at pump306 into a homogenizing buffer tank at stage 417 to conditionnanofiltration and/or reverse osmosis feed water. This will convert muchof the bicarbonate to carbonic acid and dissolved carbon dioxide as wellas increase the solubility of calcium carbonate due to the lower pH. Inestimating the acid concentrations for pH adjustment, the rule of thumbis that lowering the feedwater pH to between 6.0 and 6.5 will reduce thebicarbonate concentration by about 80%. For most CBM waters and typicalpilot program nanofiltration and/or reverse osmosis permeate recoveries,an 80% reduction of bicarbonate will be sufficient to prevent calciumprecipitation.

By inline injection of a fouling and scaling inhibitor (such as VITECH3000) at stage 421 into the nanofiltration feed stream, colloidal andscale crystal growth is slowed, colloidal formation inhibited, and thecrystalline shape of the scale crystal is modified. By inline injectionof a scaling inhibitor (such as VITECH 4000) at stage 427 into thereverse osmosis feed stream, scale crystal growth is slowed andcrystalline shape is modified. It should be realized that scaling byother salt types can occur simultaneously (for instance, BaSO₄).Therefore, it is necessary for the hybrid dosing to catch the remainingscaling causing salts with an antiscaling medium. Common scaleinhibitors consist of molecules that contain carboxylic or phosphatefunctional groups. Lower molecular weight polyacrylate molecules containmultiple carboxylic functional groups.

At reverse osmosis implementation of stage 429, membranes 2903 and 2905are preferably spiral wound polyamide skin layer composite membraneswith a zeta potential of approximately −7 mV and a polysulfone supportlayer and standard 31 mil diamond spacers (since prefiltered feed waterwill be used). Optionally, seawater polyamide membranes with a spacerthickness of 27 mil could be utilized. The polyamide thin layermembranes are constructed with an aromatic polyamide extruded onto aless dense polysulfone substrate. The optional seawater membraneelements use a denser polyamide membrane layer with better rejectioncharacteristics.

Polyamide membranes are sensitive to oxidizing agents such as freechlorine or iodine. This requires that chlorine or iodine present in thefeedwater be removed by a reducing agent (such as sodium bisulfite inthe case of chlorine injected upstream of the reverse osmosis modules).To avoid fouling in such case, a non-oxidizing biocide like BUSAN (150to 1500 ppm) can be continuously injected in-line with the reverseosmosis feed stream. This mixture which kills bacteria, fungi and algaeis compatible with the membrane material as well as the other injectionchemicals used.

A number of parameters can affect reverse osmosis permeate flowrate atstage 429 (or stage 425 if used there also). These include watertemperature, salt concentration and membrane pressure as the feed waterflows through the system. Stage 429 is preferably configured to workwithin a minimum and maximum range of 1,000 ppm to 20,000 ppm TDS, aswell as a temperature range of 40° to 80° F. The system's maximum designpressure is around 1,000 psig.

Higher pressures result in higher permeate flowrates and better saltrejection characteristics. Higher pressures also require more power andcan result in higher membrane fouling rates and reduced membrane lifeexpectancy. These considerations are important considerations forprogramming at steps related to upsizing (to full size plant). Inaddition, higher pressure operation may require stainless steel,fiberglass/epoxy or carbon fiber/epoxy membrane housings and pipingmaterial to handle the higher pressure. To maximize flexibility, reverseosmosis systems configured for high pressure operating capabilities areoften preferred.

Membrane 2903 housings are arranged vertically rather than horizontally,and all are top fed. This operating geometry provides gravitationalassistance to the high speed crossflow turbulence. Crossflow(recirculation flow) is provided by pump 2913 and flow controlled bybypass valve 2919. System pressure is controlled by pressure regulator2920. Pressure pump 2911 operates at a maximum flowrate of 2.65 GPM at amaximum 1,029 psi.

In facilities that employ high speed gravity assisted geometries intheir system design, membrane systems are working with an unconventionalhigh crossflow velocity, and the membrane housings are geometricallyarranged in a vertical top feed position. Therefore, it allows the feedwater crossing the membrane with the assist of gravity, whereby thechosen array minimizes the pressure differential across the membranesystem. This differential would otherwise take away from the net drivingpressure at the tail end of the individual membrane system.

A portion of the concentrate is recycled back to the overall membranesystem feed to increase recovery beyond the 75% it may have alreadyachieved. For example, by recycling only ⅕ of the concentrate back tothe feed, recovery can be increased to an 80% permeate recovery. Thisresults into a 20% reduction of disposable concentrate production. Theconcentrate recirculation (retentate) flow rate for the pilot unitoperation is provided through the crossflow pumps 2909 for thenanofiltration at stage 423 and 2913 for the reverse osmosis at stage429.

In order to provide the desired high crossflow velocity over themembranes, and in accord with another aspect of this invention, separatehigh flow, low pressure crossflow pumps are utilized. Since pressurepumps 2907 and 2911 of the membrane system cannot fulfill theserequirements, separate low pressure but high flow crossflow pumpsoperating in a high pressure environment with flowrate adjustmentcapability are needed. These pumps are magnetically driven with no sealsand are equipped with high pressure stainless steel housings to containa feed pressure of up to 1200 psi. The relatively small, low energy,high pressure feed pumps provide the system operating pressure. The feedpressure and flow rate is preferably regulated by a vector drive.

Through this arrangement, the feed achieves sufficient pressure throughthe high pressure feed pumps for membrane separation. These high flowcrossflow pumps provide sufficient turbulence and hydrodynamic shear toflush down and clean out the membrane flow channels of contaminatedmatter to minimize any fouling/scaling potential of the specificmembrane system. The low operating pressure of the crossflow pump doesnot create excessive pressure even when operated at full flow capacity.Crossflow meters are preferably utilized to measure, control, and obtainoptimum crossflow and crossflow velocity to achieve sufficientturbulence to minimize fouling/scaling potential. Turbine meters withmagnetic pickups and transmitter/read-out units are preferred. Thepreferred pumps here are magnetically driven centrifugal pumps. The highflowrate is needed to cover a large crossflow rate range. The flowrateis easily adjustable through a valve controlled by-pass.

Turning to FIG. 8, the preferred magnetically driven centrifugal pump3001 (used, for example, for pumps 2909 and/or 2913) of this aspect ofthe invention is illustrated, such pumps being heretofore commerciallyunavailable that can operate in a high pressure environment (over 500psi for the nanofiltration, and in excess of 1,000 psi for reverseosmosis). All high pressure parts are manufactured from compatiblenonmagnetic stainless steel series 316 or 312, 316L or Hastelloy C4(casing sections 3005, 3013 and 3016, for example). Nonmagneticstainless steel is required to contain the high operating systempressure, to offer corrosion resistance in a chloride rich environmentand to allow a magnetic field transfer, from drive magnet 3007 to magnetcapsule 3021, to facilitate the no touch magnetic coupling process.

Another novel element of the pump design herein is use of off-the-shelfplastic low pressure internal pump parts (for example, impeller 3009,mouth ring 3011, spindle 3015, rear thrust 3018, front thrust 3019 andmagnet capsule 3021). Since pump shavings from plastic impellers havebeen known to foul the lead end elements of membrane systems, anoptional discharge screen downstream of the pump is recommended. Achemically resistant coating such as Ceramic, PVDF, PP, PE, HPE, PTFE orPFA is utilized to prevent pitting and is applied to the inside of highpressure pump components.

The magnetic pump is otherwise of convention design. Ceramic spindle3015 is mounted rigidly on one end onto stationary, high pressureresisting rear casing 3016 which is made from non-magnetic stainlessalloy. Main bearing 3017 rotates on the protruding end of spindle 3015,bearing 3017 press fitted into magnet capsule 3021 which iscounter-rotationally twist-locked onto impeller 3009. Pointed conicalrear thrust 3018 is mounted on impeller 3009 and limits rearwardmovement of magnet capsule 3021 and impeller 3009. Thrust 3018 ridesagainst the front face of stationary spindle 3015 thus limiting the rearthrust. Likewise, front thrust of magnet capsule 3021 and impeller 3009is limited by impeller mounted mouth ring 3011 riding against the frontface of stationary front thrust 3019. The feed medium itself provideslubrication between moving and stationary thrust contact areas.

In accordance with another aspect of this invention, in-line degasserand degasser column assemblies 3101 are shown in FIGS. 7 and 9.Assemblies 3101 are specifically adapted for air and/or CO₂ removal orreduction in the produced membrane permeate flow stages 423 and 429 inorder to improve flow rates and flow data acquisition in the permeateproduction process. The design, use and application of these assembliesare an improvement over prior art designs and methods. Assemblies 3101condition flow of produced permeate by air/gas removal prior toprocessing through flow instrumentation and recording devices for thegeneration of real time liquid flow data without error producing air orgas content. Assemblies 3101 are adaptable in any setting where enhancedflow process stabilization is required in a liquid system with entrainedand unwanted air or gas and where in-line degassing is needed forflowmeter applications. No packing material is needed for optimumsurface area contact between the water and the air as is used inconventional tall column forced-draft degassifier designs.

Assemblies 3101 include inline degasser 3103 and attached degassercolumn 3105, and has no moving parts. Head back pressure control can beadjustable by height adjustment of elbow 3107 relative to the top ofcolumn 3105 (at cap 3109). Visual inspection of ongoing degassificationprocesses can be monitored through clear column tube 3111. Ball-valve3113 controls flow to degasser 3103 of assembly 3101, flowmeter 3115following degasser 3103. Gas supersaturated concentrate flows into thebottom of expansion chamber 3117 of degasser 3103 providing atmosphericpressure release through top connected hose 3119. Hose 3119 is connectedat the other end to degasser column 3105.

Vertical adjustment of column 3105 provides proper back-head,back-pressure control, the column's horizontal swivel capability atcantilever arm 3121 providing dead leg free hose transfer. Head isadjusted to match individual concentrate draw-off by keeping enoughcolumn head on column 3105, which is open to the atmosphere. As aresult, a spilling out of concentrate flow is avoided. Throughcontrolled release of back-pressure, concentrate discharge gas pressureis lowered in expansion chamber 3117.

The in-rushing expanding CO₂ bubbles towards the lower pressure level ofupper expansion chamber outlet 3123. The rising bubbles accelerateduring their ascent due to the simultaneous decline of available headpressure in assembly 3101. Since the ascending bubbles are shielded fromentering the lower water transfer openings in pipe riser 3125 by shield3127, only the descending, saturated but bubble-free water enters thetransfer openings. The now transformed water from the supersaturated tothe saturated stage is calm enough to allow for meaningful flowmeterreadings and control.

Flow distributor and discharge equalizer 3201 in accord with anotheraspect of this invention is shown in FIG. 10. The method of use ofequalizer 3201 is novelly adapted to use with high speed crossflowmembrane systems operating in a gravity assisted mode. Equalizer 3201 ishydrodynamically designed for flow direction from a horizontal entryflow at port 3203 to a vertical flow in housing 3205, and a flowdirectional change back from a vertical flow to a horizontal side exitflow to enhance operation of the vertically mounted high speed membranesystems.

Flow altering distribution cones 3207 at product tube extension 3209provide favorable hydromechanical loading and unloading for spirallywound membranes by distributing the in-rushing high crossflow of highoperating pressure more evenly into the leading portion of thevertically arranged membranes. Since favorable membrane hydromechanicsextends useful membrane life expectancy, cost savings are realized.

Equalizers 3201 are mounted in place of long sweeping mounting elbowsusually used for top entry and bottom exit of conventional high speed,vertical membrane system designs (at 3211, for example, in FIG. 7, otherutilization nodes being identifiable in the drawings). This improvedhydrodynamic design adapted for side entry operation is a practicalmethod for reducing overall height and footprint requirements of avertically mounted, high speed membrane system.

In accordance with another aspect of this invention, a first embodimentof a high frequency membrane separation apparatus and method utilizablewith membrane systems of this invention is shown in FIGS. 11 a and 11 b.This invention relates to apparatus and methods for fluid filteringutilizing membrane separation (for example nanofiltration and/or reverseosmosis filtration) that combines vibratory shear techniques withadjustable crossflow techniques. This and further embodiments of thehigh frequency membrane separation apparatus and methods (set forthhereinafter) are particularly well adapted to treatment stages 419, 423,429 and/or 433 when membrane treatment options are applied (genericallyreferred to hereinafter as membrane treatment systems).

High frequency membrane separation herein refers to vibrating,oscillatory motion of the membrane support structure. Vibrationdirection is perpendicular to the floor of the installation for gravityassisted membrane separation systems. The vibration curve is preferablya regular curve, which corresponds mathematically to a zero centeredsine or cosine, a sinusoidal or simple harmonic. The amplitude ispreferably steady and frequency high.

This hybrid does not depend solely on vibratory induced shearing forcesto prevent fouling and thus does not require total shut down of themembrane separation process during preventive maintenance on thevibrators. The shear wave produced by axial vertical membrane vibrationcauses solids and foulants to be lifted off membrane surfaces andremixed with retentate flowing through the parallel or tunnel spacer orother specially designed spacers of spirally wound elements or throughflow channels of tubular or capillar membrane elements. Movementcontinuity is maintained through the adjustable crossflow, reducingfurther additional membrane fouling tendency.

This hybrid approach using adjustable crossflow and high shearprocessing exposes membrane surfaces for maximum flux (volume ofpermeate per unit area and time) that is typically higher than the fluxof conventional vibratory membrane technology alone. In the conventionalvibratory membrane design, each membrane module requires its ownvibratory energy source. Only a single vibratory engine 3303 is utilizedfor a multi-membrane module design herein (up to thirty-two 2.5″,sixteen 4″ or eight 8″ membrane modules).

To suit certain operating environments, where height restrictions and/orleveling problems are encountered, high frequency membrane separationapparatus of this invention can be operated at an incline using centerpivot 3304 for adjustment of swivel framework 3305 (from standardvertical position to a maximum 15° incline orientation) in swivelsupport 3306. Unlike other vibratory membrane separation technologywhich employs horizontal vibratory torsional motion in the axis plane ofabscissa (x), and which require use of proprietary one source onlycustom membrane modules, this approach is more flexible. Readilyavailable, and thus less costly, conventional membrane modules can beused, and mounting of membrane modules in a vertical flow gravityassisted position with adjustable crossflow operation is accommodated.

This embodiment of the high frequency membrane separation apparatus usestwin motors connected at shaft/eccentric and weight assemblies 3307 and3309 of the motors in vibratory engine 3303 to provide shear enhancedfouling reducing membrane separation (these vibrator motors are wellknown structures). The motors are preferably 3-phase 1800-3600 RPMinduction motors delivering high speed synchronized centrifugal force,one motor rotating shaft/eccentric and weight 3307 counter-clockwise andthe other rotating shaft/eccentric and weight 3309 in a clockwisedirection.

The vibrator motors are capable of producing net centrifugal forces thatchange direction in space as the motor rotates. Such a force acts upwardat one instant and downward a half-rotation later, thus producing aforce that acts sinusoidal at a frequency that corresponds toshaft/eccentric/weight assemblies' 3307/3309 rotation.

Adjustable eccentric weight provides variable force output (from 0% to100%) at a synchronized mode of operation (i.e., the adjustable weightsare aligned with each other at 90° for clockwise rotation and 270° forcounter-clockwise rotation). A vibratory high-speed linear motionthrough center of gravity thus impacts swivel framework 3305 having thevibrating motors mounted on the inside thereof and the membrane modulesmounted on the outside thereof.

Support box frame structure 3310 is preferably square tubing 2″×2″ witha ⅛″ wall. Frame structure 3310 carries membrane modules (hereinafter3311, generally applied, for example, to modules 2901 or 2903/2905 ofFIG. 7 or other membrane modules disclosed herein and related to thevarious nanofiltration and reverse osmosis options) and includes frameuprights 3312 mounted via rubber dampeners 3313 (preferably eight) atswivel framework 3305 (one upright per corner of the support structure).Swivel frame uprights 3315 of support 3306 are preferably made fromfabricated ¼″ steel material, and are connected to seismic absorbingmass at fabricated steel base frame 3317. Base frame 3317 is preferablyat least partially filled with concrete to add mass.

Two springs 3319 are located in-line at the top of support structure boxframe 3310 (supporting panel structure not shown) and between horizontaltop frame members 3321 of the open swivel framework 3305. Dampeners 3323are located adjacent to bottom frame member 3325 of swivel framework3305. As compared to conventional springs, urethane springs/dampenersare preferred for their high load-carrying capability, longer life,abrasion resistance, low noise, and vibration damping and shockabsorbency.

The springs themselves are cylindrical, and four connecting bolts 3327fasten support structure 3310 to swivel framework 3305. Thefine-threaded connecting bolts allow for vibratory amplitude adjustmentin a range up to about 1″. If combined with conventional coil springs,the vibratory amplitude adjustment range increases up to 1.5″. Togetherwith the adjustable frequency drive (or inverter drive), customizationof axial vibratory linear motion for shear enhanced fouling reducingmembrane separation is accommodated.

A second embodiment of the high frequency membrane separation apparatusand methods of this invention is shown in FIGS. 12 through 16. In theembodiment shown in FIG. 12, vibration is hydrodynamically controlled.This embodiment is specially applicable whenever a homogen dispersefluid substance with a lower concentration polarization layer has to betreated—for instance, organic and inorganic colloidal solution as wellas fine disperse suspensions and higher concentrations of salt solutions(TDS 1,000-50,000 mg/L). Since high shear rates are not required in highfrequency membrane separation apparatus 3401, apparatus 3401 can beconfigured to operated at a lower amplitude. System 3403 can operateefficiently at a lower amplitude.

Vibratory impulse energy is provided through the primary feed pump (forexample, pumps 2907/2911 as shown in FIG. 7), no secondary vibratoryenergy source is required. Furthermore, only the membrane, fluid column(preferably pre-filtered as taught herein, generally represented at3404) and some associated internal components of apparatus 3401 arevibrated (not the entire unit including support mass). One feed pump2907/2911 can serve one or many modules in parallel feed array.

In combination with heretofore described crossflow characteristics,hydrodynamic vibration herein provides axial vibration of amplitude “Y”to enhance the sinusoidal flow pattern between transverse spacer rods3801 in membrane media 3802 (see FIG. 16). Vibration amplitude iscontrolled through stroke adjustment. The system operates with lowvibratory energy waves which are scaled to provide effective agitation.Axial vibration with a maximum amplitude Y of only about 2 mm for aspirally wound membrane is sufficient to maintain proper permeatecontinuity. Apparatus 3401 provides sinusoidal meandering turbulentcleaning action by high frequency vibration up to 180 Hz in a tangentialdirection to the surface of the membranes (see FIG. 16).

To affect the benefits of hybrid apparatus 3401 membrane element 3405 isoscillated within the membrane housing 3407 (see FIGS. 13 through 15).The bulk stream containing the returned suspended particles between themembrane leaves of spirally wound membrane elements (generally at 3803in FIG. 16), and in the flow channels of tubular and/or capillarymembrane elements, is continuously flushed out of the membrane module bymeans of the gravity assisted low crossflow. Since apparatus 3401 doesnot depend on crossflow induced turbulence, feed of a homogen fluidsubstance with a lower concentration polarization layer can beconcentrated at a higher level.

Crossflow pressure can be maintained in a low range between 35 and 140kPa (utilizing crossflow pump 2902/2913, for example) thus producing anadjustable low crossflow velocity in the range of 0.075 to 1 m/s andrequiring low operating energy. Sufficiency of turbulence foranti-fouling/scaling is maintained by high frequency of the vibration.Produced are low vibratory energy waves scaled to provide a nonstagnantmembrane area environment with effective sinusoidal meanderingturbulence to the boundary layer 3805 area, settling of suspendedparticles thus inhibited.

Feed activated hydrodynamic impulse system 3501 is best illustrated inFIGS. 13 through 15. A pulsating high pressure water jet is receive fromplunger pump 2907/2911 through inlet port 3503 through lower retainerring 3504 and feed ring-room housing 3505 at lower section 3506. Housing3407 holding filter module 3405 is ported as required for feed input andconcentrate and permeate output and is constructed accordingly. Uppersection 3601 (FIG. 14) includes permeate discharge connector 3603, upperretainer plate 3605, spring rings 3606, bolt retainer plate 3607, springadjustment plate 3609, return spring 3611 and lantern ring 3613.Variously sized O-rings seals 3615 seal the unit. Membrane coupling 3617couples connector 3603 to membrane 3405.

Lower section 3506 (FIG. 15) further includes permeate tube plug 3703,ring piston 3705, retentate discharge connector 3707, and spring rings3709 and 3711. Again, various sized o-rings 3713 seal the apparatus. Ascan be appreciated the pulsating jet of water received through port 3503vibrates module 3405 at ring piston 3705 at the rate of pulsation.Reciprocation is limited and maintained by spring 3611 operating againstring 3613 (held in adjustment by adjustment plate 3609).

Self-contained, vibratory spring, seal and transfer conduit apparatusand methods, in accord with yet another aspect of this invention, areillustrated in FIGS. 17 and 18. The self contained, vibratory spring,seal and transfer conduit apparatus and methods of this inventionprovide a flexible sealing connection between an oscillating and astationary object by means of a fluid conveying elastomeric conduitconnection. The flexible fluid conveying conduit is equipped withnonflexing end connectors to provide motionless sealing surfaces for theassociated o-ring seals which are housed in the respective objects. As aresult, positive nonreciprocating sealing in a dynamic operatingenvironment is provided.

Self contained apparatus 3901 is adapted for (but not limited to) usewith vibrating membrane technology of the type shown herein in FIG. 13(and numbers therein common to both embodiments are carried forward).Apparatus 3901 is preloaded under tension by a polyurethane basedpermeate transfer conduit 4003 (also referred to herein as polyurethanespring conduit 4003). The material used has a durometer of about 60 Aand has high rebound values (greater than 65%) sufficient to withstandhigh frequency vibrations. The materials is selected to have high loadbearing properties in both tension and compression). All machineelements thus remain in alignment and remain stationary (relative to oneanother) thereby preserving sealing surfaces while the vibratory load isoperating.

Springs (preferably Belleville or disc springs) 4005 generate a portionof the compressive force counter reacting the tension load ofpolyurethane spring conduit 4003. Pre-load retainers 4007 preferablystainless steel retainer rings or spring clips) contain and securepreload, connecting urethane spring conduit 4003 with the upper andlower load guides 4009. Springs 4005 are held between upper and lowerload guides 4009 and center load guides 4011, load transfer spacer 4013spanning center guides 4011 spacing the two spring columns (formed by aspring 4005 and one each of load guides 4009 and 4013). This arrangementequally distributes the low value tension and compression loads.

Spring 4015 further supports polyurethane spring conduit 4003. Conduit4003 is mounted at the upper end with a modified plate 4016, abuttingmodified permeate discharge connector 4004, and at the lower end to amodified lantern ring 4017. Load transfer spacer 4013 has a lengthselected so that maximum urethane spring conduit 4003 deflection is lessthan 2%. Urethane spring manufacturers suggest a maximum deflection of25% and a maximum cycle rate of 700 cycles per hour for intermittentoperation. For continuous operations and a maximum deflection of 15%, amaximum cycle rate of 12,000 cycles per hour is suggested. Becauseapparatus such as apparatus 3901 has a cycle rate of between 216,000 and648,000 cycles per hour, the deflection percentage needs to besignificantly reduced.

Apparatus 3901 provides wear and leak-free operation for permeate fluidtransfer between oscillating membrane element 3405 and its stationaryhousing 3407 components, thus effectively avoiding contamination of theproduced permeate with feed water. Apparatus 3901 accommodates eitherhigh frequency membrane separation housing designs (side port entry andthe top port entry) and serves as a return spring for apparatus 3401 aswell as a permeate transfer conduit and seal unit. Modular designaccommodates ease of maintenance.

On the lower side of apparatus 3901, lower spring 4005 column oscillatessimultaneously with the module 3405, while at the upper side ofapparatus 3901 upper spring 4005 column remains steadier so that theconnecting end of conduit 4003 remains motionless in its sealing seat4019. This is due to the return spring pressure acting upon the upperretainer which keeps the upper male connecting end securely in itssealing seat.

In accordance with yet another aspect of this invention, FIGS. 19 and 20illustrate a high shear and high amplitude internal membrane separationapparatus and methods. This invention relates to permeate continuity inwater treatment processes. More particularly, the purpose of this aspectof the invention is to achieve high shear in such processes to increasepermeate continuity while treating high load of colloidal and slimymatter (polysaccharide, etc.) in treatment station feed water.

Apparatus 4101 illustrated in FIG. 19 offers high shear operation forinternally vibrating membrane separation systems of the types heretoforedisclosed. This high shear option is provided by means of a highvibration amplitude in the range of 1/32″ to ⅜″. However, such highamplitude vibration could damage membrane element 3405. Thus, in accordwith this invention, an all-surrounding membrane support tube 4103 withupper and lower connecting end pieces 4105 and 4107 which are rigidlycoupled and locked to support tube 4103 by split tongue and groove rings4109 are provided, thus converting membrane element 3405 into membranecartridge 4111 having element 3405 therein. Membrane cartridge 4111provides a backlash free, non-load bearing and non-force transmitting,hardened operating environment for membrane element 3405.

End pieces 4105 and 4107 also provide means for membrane fluid transfer.Upper end piece 4105 has two conduits 4113 for crossflow feed influentand 4115 for produced permeate effluent. Lower end piece 4107 hasmultiple inclined conduits 4117 (at least four conduits for smallermembranes) all merging into large retentate effluent conduit 4119 ofventuri nozzle 4121. Nozzle 4121 has an outside cone angle of about 21°to support venturi function and enhance rapid transfer of the pulsating,make up feed flow at elevated operating frequencies. High pressurevibrating pulsating feed input 4123 through lower flange and injectorbody assembly 4124 is positioned to operate against surface 4125 oflower end piece 4107 to vibrate cartridge 4111.

Overall, a containment housing 4127 is welded to transfer flangeassemblies 4129 (upper) and outer flange 4130 of assembly 4124, thelower flange assembly bolted together by bolt and nut sets 4131 throughlower inner flange 4132 and outer flange 4130 of assembly 4124. Upperflange assembly is bolted together with bolt and nut sets 4133 havingrecoil springs 4135 thereover for recoil adjustment. Safety guard 4137is mounted at the top of apparatus 4101 and includes a window foron-site amplitude inspection.

The structural integrity of the membrane element 3405 needs to be strongenough to sustain its own vibratory mass acceleration forces within itshardened enclosure. To provide maximum structural membrane elementstrength, the preferred spirally-wound membrane element design for allhigh frequency membrane separation applications in high shear modeincludes fiberglassed outside for holding element 3405 together.However, amplitudes greater than ⅜″ are not recommended for thespirally-wound membrane elements under any circumstances since adhesivemembrane joints fatigue prematurely at higher operating frequencies (60Hz).

Apparatus 4101 allows operation of vibratory membrane implementations athigher shear at moderate frequency (20 to 60 Hz). Membrane cartridge4111 is relatively light and vibrates internally at an adjustable up toa relatively high frequency within housing 4127 (rather than vibratingthe entire heavy membrane module as is common in conventional vibratorymembrane separation processes).

A primary application for this high shear option for high frequencymembrane separation systems is the effluent treatment of dewateredelectrocoagulation sludge. This is an important treatment step whenevera required electrocoagulation process generates sludge and the producedsludge requires dewatering prior to disposal. Any other applicationwhere an elevated shear energy requirement for treatment of a specificfeed water is diagnosed would benefit from use of apparatus 4101.

A secondary application for this high shear option exists whereelectrocoagulation pre-treatment is abandoned in favor of standardnanofiltration treatment. This will produce a concentrate havingcolloidal loading too high for standard low shear high frequencymembrane separation processes. Yet another application occasioned in anycircumstance where limited disposal options are present in extreme highflow yield (high concentration factor) treatment setting.

End pieces 4105 and 4107 are preferably machined out of any suitablematerial such as metal alloys or engineering plastic materials (selectedto keep the vibratory mass low). To minimize an unbalanced, one-sided,membrane feed flow channeling, antichanneling flow distribution plug4139 having splash dome 4141 blocks direct throughflow and guides thefeed flow into ring room flow distribution channel 4143 defined at endpiece 4105. Splash dome plug 4139 rests on a shoulder in the lowersection of feed conduit 4113 and is secured in its upper position bystainless steel retainer ring 4142. A flared fluid transfer opening fromring room 4143 faces towards the anti-telescoping device at the lead endof membrane element 3405.

Step bore 4145 in end piece 4105 seals (at o-ring 4147) the upper end ofpermeate collection tube 4149. The outside of upper end piece 4105includes groove structures, the first to receive upper reciprocatinggroove ring seal 4151 to seal the upper portion of membrane cartridge4111. A second high and shallow groove 4153 receives the overlappingsplit tongue ring 4109 (connectable at its other end in groove 4155 oftube 4103. The split tongue ring halves can be held together by dualspring rings or other suitable means. O-ring 4157 seal upper end piece4105 and support tube 4103.

To take up axial slack and minimize movement of membrane element 3405within its all-surrounding enclosure, shims can be added to flowdistribution and screen plate 4159 sandwiched between upper end piece4105 and the anti-telescoping device at the lead end of membrane element3405. (and where applicable, at the permeate collection tube). Membraneelement backlash is thus virtually eliminated.

Plate 4159 provides the necessary pressure drop for proper crossflowfeed distribution around the feed ring room. In conjunction with antichanneling flow distribution plug 4139, plate 4159 minimizes localizedfeed channeling, thus utilizing more efficiently the available membranearea for diffusive fluid transfer. Plate 4159 also acts as a crossflowpump discharge filter screen to catch any particles and foreign objects.

Support tube 4103 can be made from a thin-walled metal alloy a heavierwalled, suitable plastic material in order to reduce the vibratory mass.Support tube 4103 is grooved at it bottom end (at 4155) to provide aconnection sites for tongue and groove ring 4109 thereat. U-cup sealgasket 4161 is placed around the outside (in a concentrate seal holder4162) of the lead end of the membrane element 3405. This gasket sealsmembrane element 3405 to external support tube 4103 and prevents thecrossflow feed influent from bypassing the membrane element.

Downstream, membrane element 3405 is equipped with an anti-telescopingdevice that is connected to lower end piece 4107 by means of theextended lower end of its permeate collection tube 4162. Tube 4162 issealed at o-ring 4163 at lower end piece 4107. Lower end piece 4107itself is rigidly coupled and sealed to support tube 4103 in the samemanner as upper end piece 4105. The top face of lower end piece 4107 isequipped with a tapered, shallow ring groove 4165. Groove 4165 collectsand distributes concentrate/retentate fluid through multiple inclinedfluid transfer conduits 4117 which are distributed around groove 4165.

Protruding venturi nozzle 4121, is fitted in inlet chamber 4166 which isdefined by injector body 4167 of assembly 4124 protruding into lower endpiece 4107 leaving a small ring room 4169 adjacent surface 4145 of endpiece 4107 for the distribution of the high pressure, pulsating make upfeed flow. Venturi nozzle 4121 has an effective sealing lengthequivalent to the maximum operating amplitude.

End piece 4107 has a dual purpose concentric guide shroud 4171 providinga close fit concentricity between the axially vibrating lower end piece4107 and non-vibrating injector body 4167. Shroud 4171 defines areasonable operating clearance between end piece 4107 and externalhousing 4127 to ensure proper operation of reciprocating seal 4172sealing housing 4127 and vibrating membrane cartridge 4111 frompotential fluid loss. Shroud 4171 also provides impact surface 4173contacting amplitude regulating impact ring 4175. Ring 4175 ispreferably made from polyether-based urethane (60 on the Shore A scale),providing shock deadening. Ring 4175 is configured and positioned forhighly resilient operation providing quick recovery in high-frequencyvibration applications (rebound values from 50 to 70%). Vibrationamplitude ranges can be regulated by ring height selection. An increasein ring height increases the volume of the distribution ring room 4169while reducing the effective height of the cylindrical shaped section ofnozzle 4121.

In operation, the unchanged volume of the displacement stroke of highpressure piston pump (2907 or 2911, for example, in FIG. 7) first fillsthe volume of ring room 4169 with feed liquid before it starts toinitiate an axial, upward movement of membrane cartridge 4111. Once thecartridge travel upwards and exceeds the reduced height of the outerdiameter of nozzle 4121, a fluid transfer passage around nozzle 4121(from ring room 4169 to chamber 4166) opens and passes the liquid whichthen flows by the 21° cone-shaped end of nozzle 4121 of lower end piece4107. Consequently, the feed flow through this transfer passage isentrained and carried along by the venturi effect of theconcentrate/retentate discharge and is subject to the priming suction ofthe crossflow recirculation pump (2909 or 2913, for example, in FIG. 7).

Injector body 4167 is also preferably a unitary structure, machined, forexample, from either suitable metallic alloys or plastic material.Injector body 4167 has large conduit 4177 and smaller conduit 4179,conduit 4177 for transfer of concentrated retentate and the pulsating,make up feed influent to crossflow recirculation pump as discussedhereinabove. Conduit 4179 is the input for the vibration inducing feed.Injector body 4167 is sealed at outer housing 4127 with o-ring 4181.Camber 4166 tapers down at conduit 4177 to funnel the flow intorecirculation suction connector pipe 4183 maintained through inner lowerflange 4132.

Injector body 4167 is positioned and kept in place inside externalhousing 4127 by flange 4132. The weldment of flange 4130 and housing4127 could be replaced by an integral structure such as a pipe spool. Anupper impact and buffering ring 4185 (made from a polyurethane material)is located between upper end piece 4105 and upper inner flange 4186 offlange assembly 4129 (the weldment of flange 4187 of assembly 4129 tohousing 4127 could also be replaced by an integral structure such as apipe spool).

While not preferred, a potentially useful alternative draw offarrangement for apparatus 4101 as illustrated in FIG. 20 could beutilized. This arrangement provides secondary retentate conduit 4201 inconduit 4183 and through injector body 4167 and chamber 4166 defined bylower end piece 4107 so that its inlet 4203 resides above venturi nozzle4121 in conduit 4119. In this way draw off received through cartridge4111 can be at least partially segregated from mixed retentate and feedreceived during operations from ring room 4169.

As may be appreciated from the foregoing apparatus and methods areprovided for mechanical (motorized or hydrodynamic) axial vibration inmembrane separation treatment of effluents wherein use of readilyavailable, membrane elements and/or modules is accommodated. Theapparatus can be mounted so that membrane modules are maintained in avertical flow gravity assisted position, and adjustable crossflowoperation may be utilized.

What is claimed is:
 1. A method for axial vibration in membraneseparation treatment of effluents comprising the steps of: locating amembrane element in a support structure; feeding effluent for treatmentinto said support structure; initiating axial vibration of said membraneelement in said support structure without securement of said membraneelement to a source of vibration; and withdrawing treated effluent fromsaid support structure.
 2. The method of claim 1 further comprising thestep of selectively providing a crossflow in said support structure. 3.The method of claim 1 wherein the step of axially vibrating said elementfurther comprises hydrodynamically vibrating said membrane element. 4.The method of claim 1 further comprising the step of locating saidmembrane element in a protective tube and axially locating said tube insaid support structure, and wherein the step of axially vibrating saidelement further comprises hydrodynamically vibrating said tube in saidsupport structure.
 5. The method of claim 1 further comprising sealingcomponents of said membrane element and said support structure.
 6. Themethod of claim 1 wherein the step of axially vibrating said elementfurther comprises vibrating said membrane element by means of a pump andspring installation.
 7. The method of claim 1 wherein the step ofaxially vibrating said element comprises the step of vibrating saidsupport structure.
 8. The method of claim 1 wherein the step of axiallyvibrating said membrane element occurs linearly in a vertical plane. 9.A method for axial vibration in membrane separation treatment ofeffluents comprising the steps of: locating a membrane element having anaxial dimension in a membrane support structure without any directattachment of said membrane element to said support structure or otherstructure outside said support structure; and vibrating said membraneelement in said support structure in said axial dimension one ofhydrodynamically, electromagnetically and mechanically.
 10. The methodof claim 9 further comprising the step of crossflow pumping of effluentat said membrane element.
 11. The apparatus of claim 9 wherein the stepof vibrating said membrane element includes the steps locating a springarrangement in said membrane support structure and pulsing fluid in saidsupport structure thereby, in combination with said spring arrangement,oscillating said membrane element in said support structure.
 12. Themethod of claim 9 wherein said support structure includes a tube forreceiving said membrane element, said tube and element together defininga membrane cartridge, and further comprising the steps of axiallymounting plural said cartridges at a frame structure and vibrating saidframe structure.
 13. The method of claim 12 wherein the step ofvibrating said membrane element includes vibrating said frame structurelinearly using at least a first motor.
 14. A method for axial vibrationin membrane separation treatment of effluents comprising the steps of:positioning a membrane module in a containment housing configured forfree axial movement of the membrane module therein; adjustably limitingextent of axial movement of said membrane module in said containmenthousing; and hydrodynamically activating axial vibration of saidmembrane module in said containment housing as limited.
 15. The methodof claim 15 further comprising locating said membrane module at a pistonstructure and vibrating said piston structure in said containmenthousing.
 16. The method of claim 15 further comprising locating a springat said containment housing to assist axial vibration.
 17. The method ofclaim 14 wherein the step of hydrodynamically activating axial vibrationincludes pulsing fluid through a fluid port at one end of saidcontainment housing to move said membrane module therein in a firstaxial direction.
 18. The method of claim 17 wherein the step ofhydrodynamically activating axial vibration includes utilizing amechanism at an opposite end of said containment housing to move saidmembrane module therein in a second axial direction.
 19. The method ofclaim 17 wherein the step of pulsing fluid includes pulsing fluid to betreatment in said containment housing.
 20. The method of claim 14further comprising the steps of feeding effluent for treatment into saidcontainment housing at one end and withdrawing treated effluent fromsaid containment housing at an opposite end.